The present application generally relates to motor control systems, and particularly addresses technical challenges regarding torque ripple compensation when operating motor control systems using feedforward control.
Industrial applications requiring low cost and high control performance typically employ complex electric drive in motion control systems, where the complexity is introduced in various components such as a power converter and an electric machine, to optimize cost. Generally, such optimization of cost leads to noise, vibration, and harshness (NVH) characteristics of the electrical machines to change, and at times exceed desirable threshold levels.
Typically, electrical machines using permanent magnet synchronous machines (PMSM), which may be operated using feedforward control, produce order tracked torque ripple (including cogging torque) due to non-sinusoidal back-EMF (BEMF) distribution of magnet flux around one or more air gaps in the PMSM. Further, imbalances between three (or more) phases of power used to operate the PMSM result in torque ripple as well. Further, several other machine-specific non-idealities result in torque ripple. Additionally, controlled induced parasitic torques also exist in the drive system of the PMSM.
Such torque ripples further cause the NVH characteristics of the PMSM to degrade. The NVH performance exceeding desirable threshold levels can cause discomfort to operators, for example if the PMSM is part of a steering system, a vehicle, home appliances, or any other system, and even make the system inoperable. Further, NVH can lead to structural damage to the system and/or surroundings. Accordingly, it is desirable to improve the NVH performance of the system.